WP15 Soil Ecotoxicology and Risk Assessment
Wednesday, 16 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(PHI-1117-720665) Toxicity of Selenium to the Soil Invertebrate Folsomia candida in Sassafras Sandy Loam Soil.

Phillips, C.¹, Checkai, R.¹, Simini, M.¹, Kuperman, R.¹, Higashi, R.², Fan, T.³, Sappington, K.⁴, ¹ U.S. Army, APG, MD, USA² University of California, Davis, CA, USA³ University of Louisville, Louisville, KY, USA⁴ U.S. Environmental Protection Agency, Washington, DC, USA

ABSTRACT- The U.S. Environmental Protection Agency (USEPA) is developing Ecological Soil Screening Levels (Eco-SSLs) for chemicals that are often found in soil at Superfund hazardous waste sites. Currently, information gaps in the toxicity database prevent development of Eco-SSLs for selenium. We investigated the effects of selenium to a soil invertebrate using an adaptation of the International Standardization Organization (ISO) test for the collembolan Folsomia candida. The ISO test was modified for use with a natural soil, Sassafras Sandy Loam (SSL) [Fine-loamy, siliceous, mesic Typic Hapludult] at pH 7.1, with sand:silt:clay ratio 70:13:17, and 1% organic matter. Selenium was added as sodium selenate, and weathered/aged in soil via alternating moist/dry cycles for 21 days. At the initiation and conclusion of each test, soil from each treatment level was collected, lyophilized, and stored at -40^oC. Soils were analyzed for selenium by liquid chromatography/inductively-coupled Argon plasma mass spectrometry (LC/MS), following nitric:perchloric digestion. Nonlinear regression models were used to correlate ecotoxicity data with selenium concentrations, retained primarily as SeO₄ in this soil. Preliminary results showed that the EC₂₀ and EC₅₀ values for juvenile production were 4.7 and 10.9 mg kg^-1, respectively. Results of this study will undergo quality assurance by the Eco-SSL Task Group before inclusion in the Eco-SSL database, and will be delivered as input toward developing an Eco-SSL for selenium and soil invertebrates.

Key words: selenium toxicity, Folsomia candida, natural soil, Eco-SSL